1. Field of the Invention
The present invention relates to the field of liquid crystal displaying, and in particular to a backplane and a backlight module and a liquid crystal display device using the backplane.
2. The Related Arts
Liquid crystal displays (LCDs) have a variety of advantages, such as thin device body, low power consumption, and being free of radiation, and are thus of wide applications, such as mobile phones, personal digital assistants (PDAs), digital cameras, computer monitors, and notebook computer screens.
Most of the liquid crystal displays that are currently available in the market are backlighting liquid crystal displays, which comprise an enclosure, a liquid crystal panel arranged in the enclosure, and a backlight module mounted in the enclosure. The structure of a conventional liquid crystal panel is composed of a color filter (CF) substrate, a thin-film transistor (TFT) array substrate, and a liquid crystal layer arranged between the two substrates and the principle of operation is that a driving voltage is applied to the two glass substrates to control rotation of the liquid crystal molecules of the liquid crystal layer in order to refract out light emitting from the backlight module to generate images. Since the liquid crystal panel itself does not emit light, light must be provided from the backlight module in order to normally display images. Thus, the backlight module is one of the key components of the liquid crystal displays. The backlight modules can be classified in two types, namely a side-edge backlight module and a direct backlight module, according to the site where light gets incident. The direct backlight module comprises a light source, such as a cold cathode fluorescent lamp (CCFL) or a light-emitting diode (LED), which is arranged at the backside of the liquid crystal panel to form a planar light source directly supplied to the liquid crystal display panel. The side-edge backlight module comprises an LED light bar, serving as a backlight source, which is arranged at an edge of a backplane to be located rearward of one side of the liquid crystal display panel. The LED light bar emits light that enters a light guide plate (LGP) through a light incident face at one side of the light guide plate and is projected out of a light emergence face of the light guide plate, after being reflected and diffused, to pass through an optic film assembly so as to form a planar light source for the liquid crystal panel.
Recently, major manufacturers have marketed curved liquid crystal television sets one after another. Generally speaking, the curved liquid crystal television sets allows for the best viewing effect from edge to edge, while a regular liquid crystal television set has generally poor capability of displaying at edges of a screen. The curved liquid crystal television has a screen that has a curved design showing a surrounding configuration toward a viewer so as to provide a wide full-view image, allowing for the same visual enjoyment at both the central portion or the circumferential portion of the screen and also reducing distortion of off-axis viewing for viewing at a short distance. Further, the curved liquid crystal television allows a viewer's viewing distance to be extended, achieving better experience of viewing. Thus, compared to the regular liquid crystal televisions, the curved liquid crystal television has advantages, including: (1) brand differentiating, (2) wider viewable angle, and (3) reducing distortion for short distance viewing.
Heretofore, the curved liquid crystal televisions that are available in the market are made by combining a curved backlight module and a curved liquid crystal panel. Due to the large-sized curved metal plate being hard to manufacture, it is common to provide a curved steel frame first and then mounting the steel frame to a flat backplane to achieve forced bending thereby realizing bending of the backlight module. This increases the cost of the backlight module and also complicates the structure of the backplane.
In view of the above discussed problems, a liquid crystal display device having a stepwise backplane is currently available, in which a stepwise backplane structure is used to obtain a desired curvature of circular arc thereby achieving bending of the backlight module. Referring to FIG. 1, the liquid crystal display device comprises a backlight module 100, a mold frame 300 mounted on the backlight module 100, a liquid crystal display panel 500 arranged on the mold frame 300, and a front bezel 700 arranged on the liquid crystal display panel 500. The backlight module 100 has a backplane 102, which is made to have a structure of a combination of a flat plate and steps. A curved light guide plate 104 is supported inside the backplane 102 to be in compliance with the curvature of the liquid crystal display panel 500. However, such a structure may cause a circuit board (X_Board) 900 not to securely fix to a bottom of the backplane 102 (as shown in FIG. 2). Further, the bottom of the stepwise backplane 102 has different distances to different positions of a TFT (Thin-Film Transistor) upper surface of the liquid crystal display panel 500, so that COF (Chip On Film) of some positions may be too short to be routed to the bottom of the stepwise backplane 102, thereby increasing the difficult of assembling.